A substantial amount of research and development effort is being devoted to the development and improvement of catalytic materials. Catalytic materials offer substantial improvements in the efficiency of the various chemical processes.
A primary objective in the development of catalytic materials is the maximization of catalytic specific surface area (catalyst area/mas). A primary method of obtaining such increased surface area is through the use of the RANEY process. In this process intermetallic compounds are employed as a starting material. The compounds contain the desired catalytic element and a less noble constituent. Through a chemical leaching process, the less noble constituent is removed leaving behind a skeletal array of the catalytic material. The resultant skeletal array has an exceptionally high specific surface area. Typical of such an approach is the production of skeletal nickel catalysts starting from an aluminum nickel compound such as Al.sub.3 Ni and using a caustic solution such as NaOH to remove a large portion of the aluminum from the compound leaving behind a nickel skeletal material having a high catalytic effectiveness.
For many applications, it is desirable to have the catalysts which are durable and long lived at elevated temperatures. For such applications, it is known to start with porous ceramic material and impregnate this material with a compound of a catalytically active metal and then to cause the decomposition of this compound to leave behind the metal in a catalytically effective form. Typical of such catalysts are those prepared by the impregnation of porous alumina with a solution of chloroplatinic acid followed by a thermal treatment to decompose the acid to leave behind a residue of catalytically effective platinum.
Another approach to catalyst preparation is described in U.S. Pat. No. 4,021,371. In this patent, an alloy between a catalytically active metal and a less noble metal is provided (for example, aluminum - 16% nickel). This material is pulverized and then treated with a caustic material such as an alkali metal hydroxide in an amount of from 0.01 to 2 times the stoichiometric amount with respect to the noncatalytic alloy component. This treatment produces a powder of compounds such as sodium aluminate and hydrated aluminum oxides when an aluminum containing alloy is treated with sodium hydroxide. Also contained within this powder is the catalytically active material in the form of paticles of an intermetallic compound. The caustic treatment is also effective in removing a portion of the catalytic material from these intermetallic particles. The resultant powder is washed until neutral and then dried at a temperature below about 100.degree. C. The resultant material is then used as a catalyst.
It is an object of this invention to provide a supported skeletal catalytic material by the chemical treatment of alloys between the catalytic material and a less noble metal such as aluminum and silicon.
It is a further object of the invention to produce supported skeletal catalytic materials which are effective at temperatures exceeding 600.degree. C.